CVE-2024-6127: BC Security Empire Path Traversal Flaw

CVE-2024-6127 Overview

BC Security Empire before version 5.9.3 is vulnerable to a path traversal issue that can lead to remote code execution. A remote, unauthenticated attacker can exploit this vulnerability over HTTP by acting as a normal agent, completing all cryptographic handshakes, and then triggering an upload of payload data containing a malicious path. This vulnerability affects the Empire Command and Control (C2) framework, which is commonly used by red teams and adversaries for post-exploitation activities.

Critical Impact

Unauthenticated remote code execution allows attackers to fully compromise Empire C2 servers, potentially gaining access to all connected agents, stored credentials, and sensitive campaign data.

Affected Products

• BC Security Empire versions prior to 5.9.3

Discovery Timeline

• 2024-06-27 - CVE-2024-6127 published to NVD
• 2025-09-25 - Last updated in NVD database

Technical Details for CVE-2024-6127

Vulnerability Analysis

This vulnerability is classified as CWE-22 (Path Traversal), which enables an attacker to access files and directories outside of the intended restricted directory. In the context of Empire C2, the path traversal flaw can be chained to achieve remote code execution by writing malicious files to arbitrary locations on the server filesystem.

The attack is particularly concerning because it requires no authentication—an attacker can impersonate a legitimate Empire agent by completing the standard cryptographic handshakes that Empire uses for agent communication. Once the handshake is complete, the attacker can submit specially crafted payload data containing path traversal sequences (such as ../) that escape the intended upload directory.

The impact of successful exploitation is severe: complete compromise of the Empire C2 infrastructure. This could grant attackers access to all connected agents, harvested credentials, operational data, and the ability to pivot to systems under the C2's control.

Root Cause

The root cause of this vulnerability is insufficient input validation and sanitization of file paths in the payload upload functionality. When Empire receives uploaded data from agents, it fails to properly validate or normalize the destination path, allowing attackers to include directory traversal sequences that write files outside the intended directory structure.

Attack Vector

The attack is executed remotely over HTTP without requiring authentication. An attacker initiates the exploit by:

1. Connecting to the Empire C2 server as if they were a legitimate agent
2. Completing all required cryptographic handshakes to establish a trusted session
3. Submitting a malicious upload request with path traversal sequences in the filename or path parameter
4. The malicious payload is written to an arbitrary filesystem location, enabling code execution

The vulnerability can be exploited by writing executable content to locations that are automatically executed by the system or by overwriting critical application files. A proof-of-concept exploit has been published and is available in the GitHub PoC Repository. For detailed technical analysis, refer to the Aceresponder Blog Post.

Detection Methods for CVE-2024-6127

Indicators of Compromise

• Unexpected files appearing outside Empire's designated upload directories
• HTTP requests to Empire C2 endpoints containing path traversal sequences (../, ..%2f, etc.)
• Modified system files or new executable files in sensitive directories such as /etc/cron.d/ or web root directories
• Unusual agent registration or communication patterns from unrecognized IP addresses

Detection Strategies

• Monitor Empire server logs for upload requests containing suspicious path patterns or encoded traversal sequences
• Implement file integrity monitoring (FIM) on the Empire installation directory and critical system directories
• Deploy network-based IDS rules to detect path traversal patterns in HTTP traffic to Empire listeners
• Review agent connection logs for anomalous cryptographic handshake patterns or connections from unexpected sources

Monitoring Recommendations

• Enable verbose logging on Empire C2 servers to capture all agent communications and file operations
• Set up alerts for any file write operations outside designated Empire directories
• Monitor for process execution from unexpected filesystem locations following file uploads
• Implement network segmentation to limit exposure of Empire C2 servers to untrusted networks

How to Mitigate CVE-2024-6127

Immediate Actions Required

• Upgrade BC Security Empire to version 5.9.3 or later immediately
• Restrict network access to Empire C2 servers using firewall rules to limit exposure to only trusted IP ranges
• Audit Empire servers for signs of compromise, including unexpected files and unauthorized modifications
• Review agent registrations and remove any suspicious or unrecognized agents

Patch Information

BC Security has released version 5.9.3 which addresses this path traversal vulnerability. The fix implements proper path validation and sanitization to prevent directory traversal attacks during payload uploads. Details of the fix can be found in the GitHub Empire Changelog. Additional advisory information is available from VulnCheck Security Advisory.

Workarounds

• Deploy Empire behind a reverse proxy with strict path validation rules that block requests containing traversal sequences
• Implement network-level access controls to restrict Empire C2 access to only authorized red team operators
• Use a Web Application Firewall (WAF) configured to detect and block path traversal attempts
• Consider running Empire in an isolated container or virtual machine environment to limit the impact of potential compromise

# Example: Restrict Empire access using iptables
# Allow only trusted operator IPs to reach Empire C2
iptables -A INPUT -p tcp --dport 443 -s TRUSTED_IP_RANGE -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP